1. Field of the Invention
The disclosed embodiments of the invention relate to wireless communication systems, and more particularly, to a front-end circuit for a wireless communication system that is compatible with both single and multiple antenna configurations, and wireless communication systems thereof.
2. Description of the Prior Art
In the wireless communications field, antenna configuration is a critical issue when constructing circuit architecture inside a chip based on system specifications. If the wireless communication specification only employs a single antenna shared by a transmission end and a receiving end, then an antenna switch will be required to separate a transmission amplifier and a receiving amplifier; if the wireless communication specification only employs two or more antennae wherein both a transmission end and a receiving end have their own dedicated antenna, then an antenna switch will not be required.
In order to save hardware production cost, the two architectures described above may be combined. FIG. 1 is a diagram illustrating a conventional dual-mode architecture configured in a first setting for a wireless communication system. Two low noise amplifiers (LNA) 102 and 104 are included in a dual-mode wireless front-end path 100 of a chip. The LNA 102 and 104 are coupled to a mixer 108. When adopting the single antenna mode, the LNA 104 will be disabled or left idle, and the LNA 102 and a power amplifier (PA) 106 will share an antenna 120 disposed outside of the chip. FIG. 2 is a diagram illustrating the conventional dual-mode architecture configured in a second setting for a wireless communication system. Another antenna 130 outside of the chip is used to receive data for the LNA 104. The antenna 120 is dedicated to transmit data for the LNA 106, and the LNA 102 is blocked from the antenna 120. For instance, an antenna switch inside the LNA 102 can separate a path between the LNA 102 and the antenna 120. Since the PA 106 can utilize the antenna 120 exclusively in this setting, another external power amplifier 122 may be employed to enhance signal power before the antenna 120.
The dual-mode wireless front-end path 100 can achieve divergent antenna configurations, but it needs to duplicate another LNA. In light of the above, the conventional architecture has to be refined, in terms of chip size and hardware cost.